The presence of smoke, fire, hazardous carbon monoxide concentrations are commonly sensed in commercially available products using several types of technologies. These products traditionally alert the occupants using loud audible alarms of loud tones which do not alert many individuals with hearing impairments. Building and fire regulations recognize this issue and mandate that public structures and rooms include bright flashing lights, also called ‘strobes’, to alert those individuals with impairments.
Regulations exist that require strobes to be mounted where they will illuminate appropriate areas such that individuals will see these lights and be able to take appropriate actions. One such regulation is included in UnderWriters Laboratory code 1971 (UL 1971, “Signaling Devices for the Hearing Impaired”, ISBN 0-7629-0790-8), which requires the strobes to have a designated intensity and to flash from 60 to 120 times per minute.
Other devices designed specifically for hearing impaired individuals alert them to conditions such as ringing telephones, intrusion alarms, doorbells, and other conditions requiring attention via visual indication with strobe lights. For examples of such devices, see the following URLs:    http://www.krownmfg.com/html/products/signal_device.html    http://www.kidde.com/utcfs/Templates/Pages/Template-53/0,8062,pageId%3D4496%26siteId%3D384,00.html
Some manufacturers sell stand-alone products that have combined smoke detection and strobe signaling into one self-contained device. These products include the Model 710 series devices from Gentex Corporation (www.gentex.com/fire_photo_pd4.html), and the First Alert Model SA100B from BRK Brands.
These devices have been shown to be quite effective to awaken and alert hearing impaired individuals, but quite ineffective when they are asleep. See Erin Ashley et al., “Waking Effectiveness of Audible, Visual, and Vibratory Emergency Alarms across all Hearing Levels,” published by Combustion Science & Engineering, Inc. Strobes are completely ineffective when hearing deficits are combined with visual deficits. If the individuals are not alerted, the results can range from inconvenient to deadly.
Current state of the art, exemplified in FIG. 1, addresses these deficiencies with technology designed to interconnect via wired or wireless connections 10 to the detection devices and alarms. These methods also include technology, exemplified in FIG. 2, to ‘listen’ for smoke detectors and translate those sounds into lower frequencies more likely to alert those with less severe impairments. One such technology is described in U.S. Pat. No. 6,658,123 to Crutcher.